Since the earliest resistive touch screen has been appeared in 1974, the touch technology develops rapidly; and at present, products with various touch principles, such as a capacitive touch screen, a resistive touch screen, an infrared touch screen, and an acoustic touch screen, have been developed in the industry. The capacitive touch screen is predominant in the current market due to its advantages of accurate and sensitive positioning, good touch feeling, long service life and multi-touch supportable.
The capacitive touch screen can be classified into self-capacitance and mutual-capacitance according to different work principles. Since the mutual-capacitance touch screen can achieve the multi-touch function, the mutual-capacitance touch screen becomes the mainstream and the developing trend of the capacitive touch screen market.
Presently, the majority of the mutual-capacitance touch screen employs the on-cell structure. Namely, the touch screen panel is attached on the exterior of the display panel. For this on-cell structure, the thickness and the weight of the whole display is inevitably increased, further reducing the light transmittance. Thus, the conventional on-cell structure does not conform to the requirement for developing trend of a thinner and lighter display.
Consequently, an in-cell capacitive touch screen is proposed, i.e., the capacitive touch screen pattern is integrated inside the display panel.
However, compared with the on-cell capacitive touch screen, in the in-cell capacitive touch screen, the distance between the electrode layer of the display panel and the electrode layer of a touch screen is closer, and thus the signal interference therebetween is more severe, such that the sensitivity of the touch screen is reduced. Consequently, the touch screen pattern structure of the conventional on-cell capacitive touch screen (the conventional touch screen pattern structure is generally formed of polygonal electrodes with straight sides) can not satisfy the requirement of touch sensitivity.